Field of the Disclosure
The present disclosure relates to a solar cell and a method for manufacturing the same, and more particularly, to a solar cell and a method for manufacturing the same where an ion-implantation method is applied.
Description of the Related Art
In recent times, as it becomes more accepted that conventional energy resources such as petroleum and coal will be exhausted within a foreseeable timeframe, interest in alternative energy sources for replacing the conventional energy resources is gradually increasing. Among them, a solar cell is spotlighted as a new generation cell using a semiconductor device for directly converting solar energy into electrical energy.
A solar cell is manufactured by forming a plurality of layers and patterning them through etching according to a predetermined design. In the manufacturing process, various methods and various process sequences may be applied.
For example, when doping predetermined conductivity type dopants into a semiconductor substrate, an ion-implantation method may be applied. In the ion-implantation method, an ion-beam comprising the dopants is fired at the semiconductor substrate to implant the dopants into the semiconductor substrate. The dopants break a lattice structure inside the semiconductor substrate, and thus necessitate a heat-treatment for recovery of the lattice structure. When a front surface and a back surface of the semiconductor substrate are doped with different dopants, temperatures of the heat-treatment suitable for the different dopants may differ. Generally, the heat-treatment is performed at the higher temperature between the different temperatures. But, the dopants needing to be heat-treated at the lower temperature are excessively diffused into the semiconductor substrate, adversely affecting the properties of the solar cell. Also, the cost increases and the process cannot be easily performed due to the higher temperature.